The oceans could shrink — Scientific NewsMarch 10, 1973
The world’s oceans may gradually shrink, slowly flowing into the Earth’s mantle…. Although the oceans are constantly being increased by water transported from the interior of the Earth by volcanic activity… certain processes such as the spreading of the seabed seem to let water seep in faster than it does. is replaced.
Update
Scientists have traced the ocean’s escape back to subduction zones, areas where tectonic plates collide and the heavier of the two sinks into the mantle. It is still unclear how much water has circulated between the deep ocean and the mantle through the ages. A 2019 analysis suggests that sea level has dropped on average up to 130 meters over the past 230 million years, partly due to the breakup of Pangea creating new subduction zones. Meanwhile, the molten rock that erupts from the mantle as the continents move apart can “rain” water returns to the oceanreported scientists in 2022. But since Earth’s mantle can hold more water while cooling (SN: 06/13/14), the mass of the oceans could decrease by 20% every billion years.